The present invention relates, in general, to a lithography method and, more particularly, to an x-ray lithography method that reduces stress-induced distortion in an x-ray lithography mask.
An x-ray lithography mask is typically used to form a pattern in a radiation-sensitive resist layer on a semiconductor wafer surface. The mask has a membrane on which a lithography mask pattern is disposed. X-ray radiation is passed through the membrane, and more particularly the mask pattern thereon, to impinge on the resist layer so that a copy of the mask pattern is formed in the resist layer.
The conventional types of membrane materials used in an x-ray mask are typically sensitive to x-ray radiation and exhibit a change in stress with cumulative x-ray exposure. This change in stress adversely distorts the lithography pattern on the mask and leads to distortion of the pattern to be formed in the resist layer. Accordingly, it is desirable to have a method that reduces stress changes in the membrane material during x-ray lithography.